1. Field of the Invention
The present invention relates to boxes such as food boxes which contain windows, blanks for making the same, and an associated method and, more specifically, it relates to windows which are defined in such a manner that the blanks may readily slide over each other during handling and manufacture so as to resist undesired engagement of a pair of blanks which could interfere with the manufacturing process.
2. Description of the Prior Art
It has been known to provide various types of boxes such as boxes employed for bakery products or other food products with windows. In general, these windows are openings in the box which may be paperboard, for example, with transparent plastic or paper material secured over these openings. This permits the contents of the box to be seen without opening the box, while resisting undesired contamination of the contents.
It has been known to provide windowed boxes with a separate cover which contains a top wall and four depending sidewalls and a base which contains a bottom and four upstanding sidewalls with a cover adapted to fit over the base such that the cover sidewalls are disposed exteriorly of the base sidewalls.
It has also been known to provide a box made from a single blank of material wherein the cover has a top wall and four depending sidewalls and the base has a bottom wall and three upwardly projecting sidewalls. When the box is in closed position, three of the cover depending sidewalls are disposed generally outwardly of and adjacent to the base upstanding sidewalls, and the fourth cover sidewall is integrally formed with the base so as to create a hinged cover.
In manufacturing such containers, it has been known to provide a generally flat piece of paperboard material which may be provided in individual sheet form or from a coil. A blank which is suitably configurated is severed from the remainder of the material with the blank having a window or windows in the desired location. These blanks are stacked vertically and are individually removed for transport to the window patch machine which secures an adhesively bonded piece of transparent plastic or paper to the blank in such a manner as to sealingly close each of the windows.
A problem which has been encountered in connection with the moving of individual blanks of the stack of blanks is that a window defining edge of one blank may come in edge-to-edge generally continuous contact with a window defining edge of another blank, thereby, causing the two edges to interlock and resist smooth separation.
In spite of the known means for automated manufacture of paperboard windowed boxes of this type, there is lacking an effective means for minimizing or eliminating undesired interengagement between blanks so as to resist efficient rapid transfer and processing of the blanks into a container.